Pharmacologic p38 inhibitors stimulate hematopoiesis in MDS CD34⁺ progenitors. MDS bone marrow–derived CD34⁺ cells from 19 patients were plated in methylcellulose in the presence and absence of p38 inhibitors SB203580 (5 μM and 10 μM), SD-282, and SCIO-469; inactive structural analog SB202474 (10 μM); and Mek-1 inhibitor PD98059 (10 μM). Colonies were scored at day 14, and results were expressed as means ± SEMs of 19 independent experiments.